With a development of a hybrid computer technique, providing a real-time synchronization/updating function for a file in use will bring a good experience to a user, when two or more systems are used simultaneously. For example, when a master system (i.e., a first system) is processing the file, the user may wish to continue his works on the current file at this time even if the first system is required to be switched to a second system for some reason. In this case, it is required to save all of the files currently opened in the master system manually or by means of a periodical automatic saving function.
The inventors has realized that there is at least a problem as follows in the prior art. During the synchronization, instantaneously updated contents may not be saved, even if the user uses the existing technique such as file automatic saving and automatic synchronization. In this case, the updated contents cannot be synchronously updated to the second system perfectly. Specifically, although the existing file synchronization technique may support the synchronization function implemented based on the saved files, the system performance may be affected if a time interval for the automatic saving is too short. Therefore, it is not possible to record any of amendments minutely, and thereby a real-time synchronization cannot be implemented practically. Furthermore, since the synchronization function in the prior art is still implemented based on the files saved in a non-volatile storage medium, implementation of the synchronization function necessarily relies on the automatic saving function. If the file is not saved instantaneously, the result of the real-time synchronization will be actually affected. Moreover, the automatic synchronization process may generally need some time to be completed. Thus, it is not possible to implement the real-time synchronization indeed.